Toe in, camber and stuff
Discussion
Please could one of you knowledgeable people explain a bit about Toe in and Camber.
Most things in set-up seem to be a compromise between one evil and another but what are they for these settings ? My front track is set parallel but the book says 10” toe in, presumably too much toe scrubs the tyres (disadvantage) but probably has a matching advantage (turn in perhaps). My camber, prior to re-bushing was set to a little under 2 degrees negative all round which is probably too negative but the car seemed to handle ok. If I set this back to the recommended 0.75 what are the benefits / disadvantages ? Measuring the temperature distribution across the tyres indicated that the outside edges were not doing a lot of work but I was nervous of adjusting without understanding the results.
Most things in set-up seem to be a compromise between one evil and another but what are they for these settings ? My front track is set parallel but the book says 10” toe in, presumably too much toe scrubs the tyres (disadvantage) but probably has a matching advantage (turn in perhaps). My camber, prior to re-bushing was set to a little under 2 degrees negative all round which is probably too negative but the car seemed to handle ok. If I set this back to the recommended 0.75 what are the benefits / disadvantages ? Measuring the temperature distribution across the tyres indicated that the outside edges were not doing a lot of work but I was nervous of adjusting without understanding the results.
Blimey how to describe this!!!!
Toe in
This is easier if looked at from above the car...imagine the wheels pointing inwards>thats toeing in. Wheels 'splayed' outwards> thats toe out.
I was told the Griff should be parrallel or *slightly* toe out, due to short wheelbase.
This is adjusted by the track rod ends therefore any garage should be able to sort.
This is what gives you wear on the inside/outside of the tyre shoulder if not set right
Camber
This is best viewed from the front of the car.
If the wheels are 'pointing' in at the top of the arches(as in lengthening the bottom wishbone) ALA racecar style thats negative camber (or there fooked LOL)
If they are parrallel ie straight up, then no camber.
Or (heavon forbid) go outwards at the top!!! then thats positive camber and would make for *interesting* handleing.
This should be set 'about 1deg negative (+-half a deg)Anymore than that and it will handle great but wear the inside edges of the car on the road.This means the harder you corner the wheel will be more parrallel and not go to positive camber
This is adjusted by loosening the top shock mount but needs a camber gauge to set. These can be bought but its a sod of a job (explain in a mo)
Caster angle
This is best described from a Mini's point of veiw.
The front tie bar from the bottom arm to the subframe can be replaced by adjustable ones and if the front wheel is *pulled* forward than that angles the whole kingpin assembly forward and this can cock up the self centreing on the car.
It's not a problem on TVR's as I dont think they can be adjusted
The adjustments are 'easy' to do but they can all affect each other
IE I would set corner weights using scales under each tyre, Adjusted by raising/lowering ride height(allow for driver/passenger)
Check for ride height( this could alter the corner weighting remember)
Adjust camber
Adjust caster (which affects your toe in)
Adjust toe in last
Its a nightmare to do properly without the fancy equipment unless you are used to doing it
I shall stand by for correction :-)
Toe in
This is easier if looked at from above the car...imagine the wheels pointing inwards>thats toeing in. Wheels 'splayed' outwards> thats toe out.
I was told the Griff should be parrallel or *slightly* toe out, due to short wheelbase.
This is adjusted by the track rod ends therefore any garage should be able to sort.
This is what gives you wear on the inside/outside of the tyre shoulder if not set right
Camber
This is best viewed from the front of the car.
If the wheels are 'pointing' in at the top of the arches(as in lengthening the bottom wishbone) ALA racecar style thats negative camber (or there fooked LOL)
If they are parrallel ie straight up, then no camber.
Or (heavon forbid) go outwards at the top!!! then thats positive camber and would make for *interesting* handleing.
This should be set 'about 1deg negative (+-half a deg)Anymore than that and it will handle great but wear the inside edges of the car on the road.This means the harder you corner the wheel will be more parrallel and not go to positive camber
This is adjusted by loosening the top shock mount but needs a camber gauge to set. These can be bought but its a sod of a job (explain in a mo)
Caster angle
This is best described from a Mini's point of veiw.
The front tie bar from the bottom arm to the subframe can be replaced by adjustable ones and if the front wheel is *pulled* forward than that angles the whole kingpin assembly forward and this can cock up the self centreing on the car.
It's not a problem on TVR's as I dont think they can be adjusted
The adjustments are 'easy' to do but they can all affect each other
IE I would set corner weights using scales under each tyre, Adjusted by raising/lowering ride height(allow for driver/passenger)
Check for ride height( this could alter the corner weighting remember)
Adjust camber
Adjust caster (which affects your toe in)
Adjust toe in last
Its a nightmare to do properly without the fancy equipment unless you are used to doing it
I shall stand by for correction :-)
old No 1 said:
I was told the Griff should be parallel or *slightly* toe out, due to short wheelbase.
Are you sure!?
I've not played about with the suspension settings on my Griff, 'cos it's used as a tourer rather than a proper 10/10ths sports car, but as a general rule toe out makes cars very 'pointy' and directional unstable.
I'd use a bit of toe-out on occasion for little, fidgetty hillclimb/sprint cars (and my Sylva Clubmans is set to a bit of toe-out), but for anything with the Griffith's reputation for bump steer, tramlining, unpredictable oversteer and general unrulyness, I'd stick to toe-in for road use to try and add a bit of stability!
For the record, the main purpose of toe in/out is simply to take up all the 'slack' in the bushes, joints and bearings on the suspension/steering. If you set to zero toe, any wear or play in the components will mean that the wheels 'wander' of their own free will, whereas a bit of toe means that they are always trying to steer in(or out) from the car's axis therefore taking up any slack. Obviously, to minimise tyre wear, the idea is to use the minumum toe setting that stabilises the tracking of each individual wheel whilst not giving excessive tyre scrub.
Provided camber isn't too extreme, tyres these days are designed to give a fairly progressive camber/grip curve - the grip doesn't start to fall off dramatically on a road tyre until you have a good couple of degrees of positive camber, but for reasons too complex to go into here, they definitely work better with a little bit of negative camber in most cases.
Actually, they give better cornering grip with a relatively huge amount of negative camber (sometimes in the region of 2 1/2 to 3 degrees negative), but tread wear would be horrendous for road use, and grip under straight line braking/acceleration is reduced because only the shoulders of the tyres are working at full capacity when you aren't cornering.
As with everthing else in life, suspension settings are a delicate compromise...increasing a setting may benefit one aspect of the car's performance, but be detrimental to another.
>> Edited by Martin_S on Friday 11th March 17:53
Thanks for the replies, especially the camber info, this tallies with how the car handled last year on the Hill, lots of grip in the corners but not a lot off the start line, and the soft Yokies show most wear on the inside edges. I will try to set 1 degree camber and parallel track for a test day an see how it handles.
I agree that for this layout you always want negative camber and toe in all round, the question is how much. It's all a compromise.
As mentioned, adding camber improves lateral grip in cornering but tends to compromise acceleration and braking. I run fairly low camber at the rear for straight line traction, but more camber at the front. The front camber compromises braking to some extent but I have four wheel braking (versus 2 wheel drive) so this is relatively less important.
The front is also set up for more camber gain on roll than the rear, so the front/outer wheel geometry is pretty good in corners. I also run more toe-in at the front to match the increased camber (the rule of thumb I use is 0.1 deg toe-in for each deg of -ve camber). Being rear wheel drive, the roll stiffness is heavily biassed towards the front so the outer wheel does almost all the work (inner wheel almost off the ground accelerating out of a corner).
What this approach does is give me as much traction as I can get out of a corner by moving all the weight transfer to the front and softening the rear suspension, and enough extra lateral grip at the front to overcome the understeer this causes. The ideal numbers will depend on weight distribution, power, grip, tyre pressure, spring/damper rates and driver preference and will vary from day to day and track to track if you really get into it, but as a starting point in the dry I run around -2.8 deg camber at the front and -1 deg camber at the rear, toe in to match.
>> Edited by GreenV8S on Saturday 12th March 12:44
As mentioned, adding camber improves lateral grip in cornering but tends to compromise acceleration and braking. I run fairly low camber at the rear for straight line traction, but more camber at the front. The front camber compromises braking to some extent but I have four wheel braking (versus 2 wheel drive) so this is relatively less important.
The front is also set up for more camber gain on roll than the rear, so the front/outer wheel geometry is pretty good in corners. I also run more toe-in at the front to match the increased camber (the rule of thumb I use is 0.1 deg toe-in for each deg of -ve camber). Being rear wheel drive, the roll stiffness is heavily biassed towards the front so the outer wheel does almost all the work (inner wheel almost off the ground accelerating out of a corner).
What this approach does is give me as much traction as I can get out of a corner by moving all the weight transfer to the front and softening the rear suspension, and enough extra lateral grip at the front to overcome the understeer this causes. The ideal numbers will depend on weight distribution, power, grip, tyre pressure, spring/damper rates and driver preference and will vary from day to day and track to track if you really get into it, but as a starting point in the dry I run around -2.8 deg camber at the front and -1 deg camber at the rear, toe in to match.
>> Edited by GreenV8S on Saturday 12th March 12:44
Well I'm only adviseing what I had been told by the dealer/factory??????????
I'm in agreement that toe in would be better.
I think(it was a few years ago now) it was parrallel to half deg toe out they said.
It was set up by the place in Hinkley that does lots of challenge cars so *should* know what works and what does not!!
I'm in agreement that toe in would be better.
I think(it was a few years ago now) it was parrallel to half deg toe out they said.
It was set up by the place in Hinkley that does lots of challenge cars so *should* know what works and what does not!!
What do you want to trouble your head with all that stuff for - take it to a Laser Alignment and pay someone to do it - If you're on the South Coast or anywhere near I had mine done today and it cost £40.00 - front of the car completely transformed.
The guy doing it owns a Cerbie - 45 mins later and the car was like new - personal male me and I'll explain.
Northern
The guy doing it owns a Cerbie - 45 mins later and the car was like new - personal male me and I'll explain.
Northern
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